The amount of heat generated by electronic parts, such as in plasma display panels (PDPs) and integrated circuit (IC) chips, has risen over recent years with an increase in performance. In electronic devices that use such electronic parts, functional impairment due to the higher temperature of such electronic parts needs to be prevented.
One typical way to prevent functional impairment due to the higher temperature of electronic parts is to promote heat dissipation by attaching a heat dissipator, such as a metal heat sink, a radiator plate, or a heat dissipating fin, to the heating element, such as the electronic parts. When using a heating element, the heating element and the heat dissipator are usually placed in close contact with a heat dissipating member therebetween to transfer heat efficiently from the heating element to the heat dissipator. The heat dissipating member is a member in the form of grease with high thermal conductivity (thermally conductive grease), a member in the form of a sheet (thermally conductive sheet), or the like.
The heat dissipating member used by being clamped between the heating element and the heat dissipator is thus desired to have excellent thermal conductivity while under the pressure from being clamped. In recent years, the pressure on the heat dissipating member when clamped between adherends such as the heating element and the heat dissipator (clamping pressure) has sometimes been a relatively low pressure of 0.08 MPa or less. A heat dissipating member that exhibits excellent thermal conductivity even when used at a relatively low clamping pressure is thus particularly desired.
Another typical way to increase the thermal conductivity of the heat dissipating member during use by being clamped between adherends such as the heating element and the heat dissipator is to provide the heat dissipating member with high flexibility, thereby increasing the close adherence between the heat dissipating member and the adherends and reducing the thermal resistance of the heat dissipating member under pressure due to being clamped.
However, using a highly flexible heat dissipating member by clamping between adherends such as the heating element and the heat dissipator leads to the problem of the components of the heat dissipating member leaking to the outside of the adherends (pump-out) because of the clamping pressure and heat from the heating element.
To address this problem, patent literature (PTL) 1, for example, discloses that during preparation of a thermally conductive silicone grease composition as a heat dissipating member, the viscosity of the composition is adjusted using liquid dimethyl polysiloxane with a particular substituent as silicone, thereby suppressing leakage of the thermally conductive silicone grease composition during the cooling/heating cycle of electronic parts.